Contract modifications are of the following types:

1. (a) Bilateral. A bilateral modification (supplemental agreement) is a contract modification that is signed by the contractor and the contracting officer. Bilateral modifications are used to-

   1. (1) Make negotiated equitable adjustments resulting from the issuance of a change order;

   2. (2) Definitize letter contracts; and

   3. (3) Reflect other agreements of the parties modifying the terms of contracts.

2. (b) Unilateral. A unilateral modification is a contract modification that is signed only by the contracting officer. Unilateral modifications are used, for example, to-

   1. (1) Make administrative changes;

   2. (2) Issue change orders;

   3. (3) Make changes authorized by clauses other than a changes clause (e.g., Property clause, Options clause, or Suspension of Work clause); and

   4. (4) Issue termination notices.